Python 对文件的加密和解密

cryptography库中的Fernet模块提供了一种简单的方法来加密和解密数据。它使用对称加密算法，其中相同的密钥用于加密和解密数据。以下是用Fernet模块对文件进行的加密和解密。

加密：

import hashlib
import base64
from cryptography.fernet import Fernet
import os

def string_to_fernet_key(input_string):
    # 使用SHA-256哈希函数生成一个固定长度的字节串
    hash_object = hashlib.sha256(input_string.encode())
    hash_digest = hash_object.digest()
    
    # 截取前32字节
    key_bytes = hash_digest[:32]
    
    # 将字节转换为URL-safe base64编码
    base64_key = base64.urlsafe_b64encode(key_bytes)
    
    return base64_key.decode('utf-8')

def encrypt_file(file_path, key):
    f = Fernet(key)
    base_name = os.path.splitext(os.path.basename(file_path))[0]
    new_file_path = os.path.join(os.path.dirname(file_path), base_name)

    with open(file_path, 'rb') as file:
        original_data = file.read()
    encrypted_data = f.encrypt(original_data)
    with open(new_file_path + '.byte', 'wb') as encrypted_file:
        encrypted_file.write(encrypted_data)
    os.remove(file_path)

def encrypt_directory(directory_path, key):
    for root, dirs, files in os.walk(directory_path):
        for file in files:
            file_path = os.path.join(root, file)
            encrypt_file(file_path, key)

# 使用
key = string_to_fernet_key("密钥")
print(key)
directory_to_encrypt = '文件夹路径'
encrypt_directory(directory_to_encrypt, key)

解密：

import hashlib
import base64
from cryptography.fernet import Fernet
import os

def string_to_fernet_key(input_string):
    # 使用SHA-256哈希函数生成一个固定长度的字节串
    hash_object = hashlib.sha256(input_string.encode())
    hash_digest = hash_object.digest()
    
    # 截取前32字节
    key_bytes = hash_digest[:32]
    
    # 将字节转换为URL-safe base64编码
    base64_key = base64.urlsafe_b64encode(key_bytes)
    
    return base64_key.decode('utf-8')

def decrypt_file(file_path, key):
    """
    解密指定路径的文件，假设原始文件为 Python 文件，解密后添加 .py 后缀。
    """
    f = Fernet(key)
    print(f)
    
    # 构建新文件的完整路径，假设原始文件是 Python 文件
    base_name = os.path.splitext(os.path.basename(file_path))[0]
    new_file_path = os.path.join(os.path.dirname(file_path), base_name + ".py")

    with open(file_path, 'rb') as file:
        encrypted_data = file.read()
    decrypted_data = f.decrypt(encrypted_data)
    with open(new_file_path, 'wb') as decrypted_file:
        decrypted_file.write(decrypted_data)
    os.remove(file_path)

def decrypt_directory(directory_path, key):
    """
    递归解密指定目录下的所有文件。
    """
    for root, dirs, files in os.walk(directory_path):
        for file in files:
            if file.endswith('.byte'):  # 只解密以 .byte 结尾的文件
                file_path = os.path.join(root, file)
                decrypt_file(file_path, key)

# 使用
key = string_to_fernet_key("密钥")
directory_to_decrypt = '文件夹路径'
decrypt_directory(directory_to_decrypt, key)